Lycoming Stuck Ring?

Discussion in 'Maintenance Bay' started by Alexb2000, Jan 8, 2014.

  1. Alexb2000

    Alexb2000 En-Route

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    I have a T206H with a Lycoming TSIO-540-AJ1A with 550 hours. I just had it in annual in Oct. and all the compressions were 70+. In the last +/- 15 hours I have noticed oil consumption increased to about 1 qt. every 4 hours. Prior it was using maybe 1 every 15ish. I naturally thought I had an oil leak. So off to the shop it went.

    They are telling me that the compression is all still good, but I have a cylinder pressurizing the crankcase and blowing the oil out of the breather. They said that they apply 80 PSI to each cylinder and on number 5 they could hear it blowing down into the crankcase. The plugs on all cylinders including 5 look perfect. Temps and other engine indications, perfect. They say I have a stuck ring. Options are to soak it in Marvel Mystery Oil OR rebuild the cylinder.

    So how does this work?

    Can you have good compression and excessive blowby?

    Seems counter-intuitive. Isn't pressure, pressure?

    Why would a ring just get stuck?

    Does Marvel work, or am I wasting labor dollars?

    They are quoting approx. 10 hours labor and about $1400 for the shop to rework the cylinder, rings, valves, etc.

    Has anyone seen this before?

    Thoughts?
     
  2. Geico266

    Geico266 Touchdown! Greaser!

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    How much oil do you run in the crank case?

    What weight oil are you using?

    MMO might work over time, but it depends on how hard and how long it has been stuck. Rebuilding #5 would be faster.

    The piston is moving so fast that the pressure escaping into the crankcase is minimal, but more than it was before. Reducing the amount of oil in the crankcase will help significantly.
     
    Last edited: Jan 8, 2014
  3. Henning

    Henning Ejection Handle Pulled

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    Yep, you can have a stuck ring and still maintain static compression. You can try MMO, but pulling it apart and cleaning the rings and lands is a better option, might as well clean the valves and seats while apart. Running LOP helps prevent these issues.
     
    Last edited: Jan 8, 2014
  4. Alexb2000

    Alexb2000 En-Route

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    Philips X/C 20/50 8-9 quarts on a cap. of 11. I have run this level since the engine was new.
     
  5. Geico266

    Geico266 Touchdown! Greaser!

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    If you try just MMO try dropping the level to 7-6 qts. I would bet the consumption drops in half.

    You could invest the $1400 into an oil seperator and return the oil coming out the blow by back into the engine while you are trying to free it with MMO.
     
  6. Alexb2000

    Alexb2000 En-Route

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    Is it worth cleaning or just redo it considering the labor? I lean this thing aggressively other than on the climb out. During those times I am pulling about 40 so I need a lot of fuel to keep it cool. I also have long climbs, sometimes 18-20K at 6-800 FPM, could that contribute to this?
     
  7. Alexb2000

    Alexb2000 En-Route

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    Being a turbo it seems that the temps get high under a heavy load with 6-7 that's why I run the higher amount.

    I have a separator, they tell me it's being overwhelmed.
     
  8. Henning

    Henning Ejection Handle Pulled

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    Well, price it out. Typically it takes a couple hours labor max (beyond the R&R which is the same) to clean it up vs replacing. Much of the time involved is letting the parts soak overnight. Once apart they may also find damage which would make replacing the only option.
     
  9. Clark1961

    Clark1961 Touchdown! Greaser!

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    Can't say yup or nope but with that much blow-by there is a fair chance that an air-oil separator will not be able to handle it.
     
  10. Henning

    Henning Ejection Handle Pulled

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    Not in a 520, typically 9-10 quarts is where it stabilizes.
     
  11. Geico266

    Geico266 Touchdown! Greaser!

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    Just a suggestion when trying to free it with MMO. The lower oil level would lower the blow by substantially, temporarily.

    :redface:Yea, I don't like that idea either. :lol:
     
  12. jesse

    jesse Touchdown! Greaser!

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    I'd probably ignore it for awhile and see what happens. If it was still an issue I'd pull the cylinder and see what it looks like. Based on that I'd either just clean it or send it out.
     
  13. Henning

    Henning Ejection Handle Pulled

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    The problem with that methodology is if the ring is broken, not just stuck, you run the risk of damaging a cylinder that was salvageable and just needed one ring replaced. Engines rarely fix themselves.
     
  14. weirdjim

    weirdjim Ejection Handle Pulled

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    Last edited: Jan 8, 2014
  15. weirdjim

    weirdjim Ejection Handle Pulled

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    If you have some reason to suspect broken and not stuck (like, say, a quart an hour of oil) then the old Costco $75 borescope inspection tool is called for. Even a couple of hours on a busted ring will leave a vertical line that is visible.

    Jim
     
  16. Geico266

    Geico266 Touchdown! Greaser!

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  17. N801BH

    N801BH Touchdown! Greaser! Gone West

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    Yup..... Great advice,,,, and nothing to lose except 5 bucks worth of MMO...And I bet it fixes it too..
     
  18. N801BH

    N801BH Touchdown! Greaser! Gone West

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    Another great suggestion...:yes:
     
  19. Alexb2000

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    Already doing the borescope, should know more about that tomorrow.
     
  20. Ted

    Ted The pilot formerly known as Twin Engine Ted

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    I've never heard of an engine fixing itself on a ring being stuck. I would typically expect to see lower compression on the cylinder, but that doesn't necessarily mean that it's required. Yes, your air/oil separator is getting overwhelmed. This was pretty much how the left engine was on the 310 before we did the overhaul last year. But, with 2100 hours on the engine, doing a top didn't make much sense, and the compressions were low on all cylinders. 8-9 quarts is a good number for a 540 (side note - your engine is a TIO-540-AJ1A, not TSIO. TSIO = Continental, TIO=Lycoming).

    If they are pretty certain that it's the #5 cylinder, then probably just have them pull it, fix what was wrong, and put it back on. For $1400 it sounds like they're talking about actually having the cylinder overhauled. Really it should only need new rings and a hone job, but they're probably going to send it to a cylinder shop where it will just get a full once over. It should be fine otherwise. But if you want to try the MMO suggestion first, don't see it causing any harm. It could help and won't hurt in your case.

    I think we've talked about your engine management before, but I forget the specifics. What is your climb power setting and what CHTs do you see? Same for cruise, with how you lean it for cruise. I would tend to think that you've got some oil coking around the ring, and that's causing the issue.
     
  21. Henning

    Henning Ejection Handle Pulled

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    That's an option, but it's not 'leaving it alone' and hoping the problem goes away.

    One can soak with MMO overnight and maybe the ring will break free, but it's not that big of a deal to pull one cylinder and clean it either. 'Magic solutions' I find to be temporary at best and often in the long run just are added to the total cost of the problem since you have to fix it right eventually. The only time I use magic solutions anymore is when there is a job time critical to get done and the solution provides a bandaid allowing that check to be collected. On a recreational use application, it usually ends up just being an additional expense with no pay off.

    BTW, if I wanted to get rid of carbon with just a liquid solution, I would chose GM X-66 or Berryman's over MMO.
     
  22. Tom-D

    Tom-D Taxi to Parking

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    Sounds to me like a broken oil control ring, if the cylinder isn't already ruined, it will be if you continue running it.

    happened too quick to be wear or a stuck ring after all the oil control ring is always running in oil.
     
  23. Alexb2000

    Alexb2000 En-Route

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    You're right, they say the cylinder shop likes to just rework the whole thing.

    I climb about 40", full rich, full prop, CHT's are cool about 330. Cruise I lean by experience vs. the lean assist. Lately in cruise 27.5", 16.6 GPH, TIT 1585, EGT 1610, CHT 380.


    That's exactly what I am afraid of. I'll see what the borescope says first, but I am leaning toward just having it pulled.

    Thanks to everyone for the great comments so far.
     
  24. Chip Sylverne

    Chip Sylverne Final Approach

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    Quit with the negative waves, man.
    I have had some success with mmo on stuck rings by using the following method:

    Ground the mags. Pull the top plug of the suspect cylinder and bring it on the compression stroke to maybe 25deg btdc. Fill the cylinder with mmo. Replace the plug. Pull the prop so that the piston compresses the mmo, kind of like hydro lock. Don't force the prop, but you should feel the compression, pushing the mmo down the cyl to the rings. Bounce it gently a couple times. Compress it and leave it overnight. Next day, pull both plugs and drain the mmo. Clean and reinstall plugs, then run the p*** out of the motor at high power settings.

    If it's a stuck rig, this works fairly well. Low cost, high return if that's the problem.
     
  25. comanchepilot

    comanchepilot En-Route

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    Gee, maybe they should just use Hoppes #9 . . .

    <jk>
     
  26. Chip Sylverne

    Chip Sylverne Final Approach

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    Quit with the negative waves, man.
    Nah, that's to clean fine wire plugs.
     
  27. Dan Thomas

    Dan Thomas Final Approach

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    I would check the oil return line from that oil separator. It might be sludged shut and the oil is filling the separator until it overflows.

    Dan
     
  28. Ted

    Ted The pilot formerly known as Twin Engine Ted

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    I seem to recall that max RPM on the AJ1A is 2500. So 40"/2500, which is a pretty high climb setting. Even in the Chieftain we'd run 40"/2400, but the highest we ever went was 11k so it didn't take as long. CHT of 330 is a good number, though.

    For cruise your manifold pressure is good. I'm not sure the RPM you're running at, but shouldn't matter a great deal. What does that mixture setting equate to in ROP/LOP terms? I'm guessing at that fuel flow it's ROP. Could be having some higher internal temps, even if CHT is only indicating 380. Do you notice any discoloration under your intake pipes? I seem to recall those engines had some hot spots in those areas because the top intake pipes blocked cooling air. It might not be a bad idea to aim for lower CHTs, especially if it could be done LOP. I've never tried LOP on an AJ1A, we should go flying sometime and see how it does. :)
     
  29. Alexb2000

    Alexb2000 En-Route

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    Good suggestion. I already had them check it and they said it's clear.

    I run 2400 in cruise, 2500 on initial climb.

    It is ROP, remember your old stomping grounds don't allow LOP:)

    I just looked today no discoloration on intake pipes, cylinder paint, etc.

    It is hard to cool the CHT's below that number and keep the cowl flaps closed. In summer I run one notch open, but not in winter.

    It will run LOP, but in order to keep any kind of speed I'll guess I would have to be around 31-32". Choices:dunno:
     
  30. Ted

    Ted The pilot formerly known as Twin Engine Ted

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    Ok, no problems there.

    Engine is out of warranty by now, isn't it? :)

    Ok, that's a good sign.

    That's about what I'd expect - a 50F-75F LOP running at 31-32" and same RPM ought to give you cooler CHTs and roughly equal speed. You'll definitely notice a speed reduction at the MP you're currently running. If you can get the same speed and lower temperatures, that makes for a happier engine long term. But since I've never flown an AJ1A LOP, I don't know how well it does it, how smoothly it runs that way, etc. As with anything, choices.
     
  31. Silvaire

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    I hope that with normal compression test readings they aren't coming to this conclusion based solely on hearing a little bit of leakage past the rings on a single test. Did they have you fly the airplane for an hour or two and repeat the test immediately after shutdown to confirm?

    Furthermore, if the problem is crankcase pressurization which is overwhelming the Oil/Vapor separator isn't a good portion of that oil going overboard going to show up on the belly? Have you seen evidence of that? Is oil dripping from the vent line after you park?
     
  32. jesse

    jesse Touchdown! Greaser!

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    +1. This is what I was getting at earlier.

    There is no way I'd yank a cylinder that had good compression without giving it a little bit of time. I'd put some effort into making damn sure that the oil is in fact blowing out the breather and isn't coming from somewhere else (clean everything really well, add UV dye).

    Once I ruled everything out I would IRAN the cylinder.
     
  33. kmead

    kmead Line Up and Wait

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    We have this problem all of the time with the Mirage and Matrix Lycoming engines. At first nobody wants to believe it's a cylinder problem. I have found the oil control ring stuck, but in most cases it's broken.

    The oil consumption will drop immediately, normally as bad as 1 qt per hour. I've seen one broken oil ring cause a consumption of 4 qts in an hour. The 2 compression rings will be good and the compression check will be 80/80. There is so much oil in the cylinder leading to great compression. Another symptom will be a bad mag check on the first flight of the day. Oil consumption is at it's worst in the flight levels too.

    What's funny is that I can pull pieces of the oil control ring and it's spring out of the suction screen but the cylinder wall is not damaged.
     
  34. Alexb2000

    Alexb2000 En-Route

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    Yes the top of the cowl flap (below the breather) is soaked. Belly is oily as well.

    I'm not trying to brag, but I keep the motor super clean as well as all of the inside cowlings. If there was an oil leak it would be obvious, especially 2 quarts of oil in last 8 hours.

    I can tell you I don't want to believe it, I didn't think Lycomings were as prone to cylinder problems. In this case I looked at all the plugs, perfect, so I don't think much oil is getting into the cylinder.

    Have you found a cause effect relationship or is this a design issue?
     
  35. flyingmoose

    flyingmoose Pattern Altitude

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    Im going to have to go with Kevin on this one.

    Maybe I missed it, but how long has this been going on?
     
  36. Alexb2000

    Alexb2000 En-Route

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    I noticed about 8 hours ago that my oil usage went up sharply to 1 qt. in every 4 hours. I assumed I had some external leak, that's why it went to the shop initially.

    Assuming it is a stuck ring, the borescope shows no cylinder damage, wouldn't it be better to deal with this now, and save the piston/cylinder vs. keep running it and possibly destroy the cylinder?
     
  37. Ted

    Ted The pilot formerly known as Twin Engine Ted

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    Yep, I'd agree there.
     
  38. Henning

    Henning Ejection Handle Pulled

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    Yes, pull the jug and deal with it. This isn't going to fix itself.
     
  39. Bill Watson

    Bill Watson En-Route

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    I'd like to interrupt this informative thread with a message from a monitoring user:

    THANKS SO MUCH to all of you for sharing all this!

    ...back to good stuff :D
     
  40. dell30rb

    dell30rb Final Approach

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    I might try the MMO if the mechanic is on board with it.

    The original quote of $1400 seems pretty high. I'm guessing that is for a full cylinder overhaul. I'd think to just pull the jug and replace a set of rings should be about $150 in parts and 3 hours labor?